QIYAS (القياس) – analogy; way of reasoning that might explain a thing by comparing it to another thing; comparison of two different things in order to find out their similarities.

PROOF

The following Hadith shows the proper procedure for applying Islamic guidance that would eventually develop into the discipline of Usul Al-Fiqh (principles of Islamic Jurisprudence). When the Prophet ﷺ sent Mu’adh bin Jabal (radiyallahu anhu) to Yemen to teach Islam to the converts there, he asked him how he will do it. Harith ibn Amr (radiyallahu anhu) reported: “Some men among the companions of Mu’adh said that the Messenger of Allah sent him to Yemen and the Prophet said: ‘How will you judge? Mu’adh said: ‘I will judge according to what is in the Book of Allah.’ The Prophet said: ‘What if it is not in the Book of Allah?’ Mu’adh said: ‘Then with the tradition (Sunnah) of the Messenger of Allah.’ The Prophet said: ‘What if it is not in the tradition of the Messenger of Allah?’ Mu’adh said: ‘Then I will strive to form an opinion (Ijtihad).’The Prophet said: ‘All praise is due to Allah who has made suitable the messenger of the Messenger of Allah.’” [Sunan At-Tirmidhi 1327, Grade: Sahih]

Amir ibn Al-As (radiyallahu anhu) reported: “I heard the Messenger of Allah say: ‘If a judge makes a ruling, striving to apply his reasoning (Ijtihad) and he is correct, then he will have two rewards; and if a judge makes a ruling, striving to apply his reasoning and he is mistaken, then he will have one reward.’” [Sahih Muslim, Book 18, Number 4261]

Other source

ISRAELIYAT (الاسرائلياتال) – came from Torah and Injil that are true and not against Islam, so they can be narrated.

Notes were accumulated from many sources and different teachers including my own notes taken during classes from long years of study. Other source was forwarded e-mails. I have no way of tracing back the origin, so this is an acknowledgement, full credits to the original writers/owners for their valuable effort. I uploaded them for archiving and personal purposes.